iov_iter: Use accessor function

Use accessor functions to access an iterator's type and direction.  This
allows for the possibility of using some other method of determining the
type of iterator than if-chains with bitwise-AND conditions.

Signed-off-by: David Howells <dhowells@redhat.com>

1 files changed, 33 insertions, 15 deletions

diff --git a/include/linux/uio.h b/include/linux/uio.h
index 422b1c01ee0d..fcabc959c794 100644
--- a/include/linux/uio.h
+++ b/include/linux/uio.h
@@ -21,7 +21,7 @@ struct kvec {
 	size_t iov_len;
 };
 
-enum {
+enum iter_type {
 	ITER_IOVEC = 0,
 	ITER_KVEC = 2,
 	ITER_BVEC = 4,
@@ -47,6 +47,36 @@ struct iov_iter {
 	};
 };
 
+static inline enum iter_type iov_iter_type(const struct iov_iter *i)
+{
+	return i->type & ~(READ | WRITE);
+}
+
+static inline bool iter_is_iovec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_IOVEC;
+}
+
+static inline bool iov_iter_is_kvec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_KVEC;
+}
+
+static inline bool iov_iter_is_bvec(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_BVEC;
+}
+
+static inline bool iov_iter_is_pipe(const struct iov_iter *i)
+{
+	return iov_iter_type(i) == ITER_PIPE;
+}
+
+static inline unsigned char iov_iter_rw(const struct iov_iter *i)
+{
+	return i->type & (READ | WRITE);
+}
+
 /*
  * Total number of bytes covered by an iovec.
  *
@@ -74,7 +104,8 @@ static inline struct iovec iov_iter_iovec(const struct iov_iter *iter)
 }
 
 #define iov_for_each(iov, iter, start)				\
-	if (!((start).type & (ITER_BVEC | ITER_PIPE)))		\
+	if (iov_iter_type(start) == ITER_IOVEC ||		\
+	    iov_iter_type(start) == ITER_KVEC)			\
 	for (iter = (start);					\
 	     (iter).count &&					\
 	     ((iov = iov_iter_iovec(&(iter))), 1);		\
@@ -202,19 +233,6 @@ static inline size_t iov_iter_count(const struct iov_iter *i)
 	return i->count;
 }
 
-static inline bool iter_is_iovec(const struct iov_iter *i)
-{
-	return !(i->type & (ITER_BVEC | ITER_KVEC | ITER_PIPE));
-}
-
-/*
- * Get one of READ or WRITE out of iter->type without any other flags OR'd in
- * with it.
- *
- * The ?: is just for type safety.
- */
-#define iov_iter_rw(i) ((0 ? (struct iov_iter *)0 : (i))->type & (READ | WRITE))
-
 /*
  * Cap the iov_iter by given limit; note that the second argument is
  * *not* the new size - it's upper limit for such.  Passing it a value